The standardization of new high-density read only and rewritable optical disks capable of recording large amounts of high-quality video and audio data has been progressing rapidly and new optical disk related products are expected to be commercially available on the market in the near future. The Blu-ray Disc Rewritable (BD-RW) and Blu-ray Disk ROM (BD-ROM) are examples of these new optical disks.
As shown in FIG. 1, user data such as A/V data and various contents is encoded through multiple data processing steps to be recorded on the BD-RW. User data of a predetermined size is converted into data frames, scrambled data frames, a data block, a long distance code (LDC) block, and a long distance code (LDC) cluster in turn.
Similarly, user control data corresponding to the user data is converted into an access block, a burst indicating sub-code (BIS) block, and a burst indicating sub-code (BIS) cluster in turn.
As shown, a BIS cluster encoded in this manner is divided into 3 parts of the same size and each part is inserted between two data blocks of an LDC cluster, each data block being of a predefined size. Sync data is added to one LDC cluster and one BIS cluster recorded in this manner, which constitutes one physical cluster.
As shown in FIG. 2, one physical cluster comprises 155 columns (sync data exclusive) and 496 rows. In each 10 row, sync data has a size of 20 bits, each of the first-column through fourth-column LDC data blocks has a size of 38 bytes, and each of the first-column through third-column BIS data blocks has a size of 1 byte. An Error in each 1-byte BIS data block can be detected by conventional Reed Solomon (RS) decoding sequences.
If there are errors in the BIS data, for example, there are errors in both of the BIS data adjacent to an LDC data block of size 38 bytes as shown in FIG. 2, it is concluded that the LDC data block contains an error and the LDC data block is marked as erasure to indicate the existence of the error.
Error correction can be done on the LDC data block marked as erasure during RS decoding operation. Consequently, an error in the LDC data that might be caused by scratches, fingerprints, etc can be corrected and user data can be normally reproduced.
The above-mentioned error correction method is only applicable to LDC data blocks in the second or third column because a data error is detected only when both BIS data blocks adjacent to an LDC data block contain errors. As shown in FIG. 2, an LDC data block (202) in the first column and an LDC data block (201) in the fourth column are adjacent to sync data and therefore error detection and error correction for those data blocks cannot be conducted.